1. Technical Field
The invention relates to a system for displaying images, and more particularly to a system for displaying images comprising an organic electroluminescent device.
2. Description of the Related Art
Recently, organic electroluminescent devices are widely applied in various display devices because they have a wider viewing angle, faster response, and a simple fabrication process. However, there is still room for improvement in terms of luminescence efficiency of the organic electroluminescent devices. Further, organic electroluminescent devices suffer from low reliability due to moisture seeping therein.
FIG. 1 shows a cross-section of an organic electroluminescent device disclosed in U.S. Pub. No. 20080129191A1, wherein the organic electroluminescent device is a bottom-emission organic electroluminescent device 100 comprising a substrate 102, a transparent electrode 106, a hole injection layer 108, a hole transport layer 110, a blue emitting layer 112, a green emitting layer 114, a red emitting layer 116, an electron transport layer 118, an electron injection layer 120, and a reflection electrode 122. The bottom-emission organic electroluminescent device 100 further comprises an optical path control layer 104 disposed between the substrate 102 and the transparent electrode 106. U.S. Pub. No. 20080129191A1 teaches that the optical path control layer 104 has a thickness of 660 nm and 750 nm, the optical path control layer 104 is disposed on the substrate 102, and the organic electroluminescent layers (including a transparent electrode 106, a hole injection layer 108, a hole transport layer 110, a blue emitting layer 112, a green emitting layer 114, a red emitting layer 116, an electron transport layer 118, and an electron injection layer 120) are disposed outside of the optical path control layer 104. Therefore, the optical path control layer 104 does not protect the bottom-emission organic electroluminescent device and does not prevent the bottom-emission organic electroluminescent device from moisture, infiltrating therein. Additionally, the problem of relieving residual stress resulting from the optical path control layer 104 is not taught.
Thus, in order to solve the aforementioned problems, a novel organic electroluminescent device is called for.